Pig Heart Attacks Raise New Fears About Cloning
by Sherry Morse
After three pigs cloned from adult animals recently died of heart attacks before reaching six months of age, new questions about the health of cloned animals are being raised.
The pigs were all created using a new technique designed to improve the efficiency of cloning. In this method, which is a variation of the technique that created Dolly the cloned sheep, a whole adult cell is inserted into a fertilized egg that has been emptied of its own genetic material.
Team leader Jerry Yang of the University of Connecticut at Storrs said that of four piglets born after this technique was used, one died within days and the other three have all since died of heart failure or what he dubbed, "Adult clone sudden death syndrome."
Yang still hopes that the whole-cell injection technique will be successful because it uses fewer eggs than the alternative technique where egg and adult cell are fused with a flash of electricity.
The new technique also has a higher success rate than other cloning methods, with nearly forty percent of the clones surviving the first few days of growth - a rate two-to-three times that of other cloning methods.
Yang believes, however, that the piglets may have experienced problems due to the fact that adult DNA is not properly reprogrammed to drive embryo growth.
He hopes to find the genes responsible, and he believes these might be found among those that govern the heart’s function.
The deaths of the piglets call into question the idea of transplanting hearts or livers from genetically altered and cloned pigs into humans.
Researchers have already produced genetically engineered, partly humanized pig cells which are then cloned to create pigs whose organs may be less likely to be rejected by human recipients.
Randall Prather of the University of Missouri-Columbia, believes that any dangers would be avoided by breeding from first-generation clones because cell reprogramming is completed when cloned animals reproduce.
© 2003 Animal News Center, Inc.
After three pigs cloned from adult animals recently died of heart attacks before reaching six months of age, new questions about the health of cloned animals are being raised.
The pigs were all created using a new technique designed to improve the efficiency of cloning. In this method, which is a variation of the technique that created Dolly the cloned sheep, a whole adult cell is inserted into a fertilized egg that has been emptied of its own genetic material.
Team leader Jerry Yang of the University of Connecticut at Storrs said that of four piglets born after this technique was used, one died within days and the other three have all since died of heart failure or what he dubbed, "Adult clone sudden death syndrome."
Yang still hopes that the whole-cell injection technique will be successful because it uses fewer eggs than the alternative technique where egg and adult cell are fused with a flash of electricity.
The new technique also has a higher success rate than other cloning methods, with nearly forty percent of the clones surviving the first few days of growth - a rate two-to-three times that of other cloning methods.
Yang believes, however, that the piglets may have experienced problems due to the fact that adult DNA is not properly reprogrammed to drive embryo growth.
He hopes to find the genes responsible, and he believes these might be found among those that govern the heart’s function.
The deaths of the piglets call into question the idea of transplanting hearts or livers from genetically altered and cloned pigs into humans.
Researchers have already produced genetically engineered, partly humanized pig cells which are then cloned to create pigs whose organs may be less likely to be rejected by human recipients.
Randall Prather of the University of Missouri-Columbia, believes that any dangers would be avoided by breeding from first-generation clones because cell reprogramming is completed when cloned animals reproduce.
© 2003 Animal News Center, Inc.
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